Electronic valve reader

ABSTRACT

The invention is directed toward a magnetic valve reader used as an indicator tool. The magnetic valve reader determines a location and an orientation for a magnetic indicator device to indicate a device setting of an implantable medical device. The implantable medical device includes the magnetic indicator device coupled to a valve on the implantable medical device. External magnetic fields, specifically the Earth&#39;s magnetic field, may interfere with the compass and create an incorrect device setting indication. The electronic reader estimates the external magnetic fields to subtract the estimate from received data to minimize any influence that external magnetic field has on the accuracy of the device setting measurement.

FIELD OF THE INVENTION

The invention relates to medical devices and, more particularly, tomagnetic reader-based indicator tools.

BACKGROUND

Magnetic-based indicator tools are used to determine a setting of animplantable medical device. The implantable medical device may include afluid flow control valve that controls the pressure of cerebral spinalfluid (CSF) in a patient's brain. Excessive accumulation of cerebralspinal fluid (CSF), due to hydrocephalus or other causes, manifestsitself as increased pressure within the brain. Relieving the CSFpressure is therapeutically beneficial and is usually done by using afluid flow control valve to drain CSF from ventricles in the brain.

The implantable medical device may include a target in the form of amagnet. The magnet allows a tool set to determine the setting of themedical device and change the setting without removing thesubcutaneously implanted device. The tool set typically includes alocator tool to determine the orientation of the medical device, themagnetic-based indicator tool to determine the setting of theimplantable medical device by using a compass, and an adjustment tool tochange the setting of the medical device by using another magnet. Thetool set works by using magnetic coupling between the magnet on theimplantable medical device and each of the indicator tool compass andthe adjustment tool magnet.

The compass-based indicator tool relies on an interaction between themagnet on the medical device and the compass that is strong enough todetermine the position of the magnet even through a patient's scalp. Themagnet-compass interaction must also be resistant to external magneticfields, especially from the Earth. The compass will drift towardaligning with the Earth's magnetic field if the pull of the magnet inthe implanted medical device is not strong enough. The deflection angleincreases as the distance between the magnet and the compass increases,and may lead to inaccurate device setting indications.

Alternatively, magnetic based location tools have been developed todetermine the three-dimensional location and orientation of magneticdevices within implanted medical devices, such as medical tubes andcatheters. These alternate location systems typically do not relate tothe rotatable orientation of magnetic devices that are part ofimplantable valve devices.

U.S. Published Patent Application No. 2002/0022793 to Bertrand et al.discloses a compass-based indicator for assessing the position of afluid flow valve within an implanted device. The fluid flow valvedescribed by Bertrand et al. may be used for controlling the flow ofcerebral spinal fluid (CSF) in a patient with hydrocephalus. Thiscompass-based indicator is used in combination with an implantable flowcontrol device disclosed within U.S. Pat. No. 5,637,083 to Bertrand etal. U.S. Pat. No. 5,879,297 and U.S. Pat. No. 6,129,668 to Haynor et al.discloses an electronic device to determine the location and orientationof a magnet coupled to an indwelling medical device using a plurality ofmagnetic sensors. Table 1 below lists documents that disclose devicesfor determining the location and orientation of magnetic devices withinimplantable medical devices.

TABLE 1 Patent Number Inventors Title U.S. Pat. No. 5,637,083 Bertrandet al. Implantable Adjustable Fluid Flow Control Valve U.S. patentapplication Bertrand et al. Tool for Adjusting an Ser. No. 2002/0022793Implantable Adjustable Fluid Flow Control Valve U.S. Pat. No. 5,879,297Haynor et al. System and Method to Determine the Location andOrientation of an Indwelling Medical Device U.S. Pat. No. 6,129,668Haynor et al. System and Method to Determine the Location andOrientation of an Indwelling Medical Device

All documents listed in Table 1 above are hereby incorporated byreference herein in their respective entireties. As those of ordinaryskill in the art will appreciate readily upon reading the Summary of theInvention, Detailed Description of the Preferred Embodiments and claimsset forth below, many of the devices and methods disclosed in thepatents of Table 1 may be modified advantageously by using thestructures and techniques of the present invention.

SUMMARY OF THE INVENTION

In general, the invention is directed to an electronic device fordetermining the location and orientation of magnets coupled toimplantable medical devices. The electronic device is included in amagnetic-based indicator tool for interaction with an implanted medicaldevice to assess a setting associated with the device. The invention hascertain objects. That is, various embodiments of the present inventionprovide solutions to one or more problems existing in the prior art withrespect to the magnetic-based indicator tools for interaction withimplanted medical devices.

The problems include, for example, inaccuracies in the settingindication provided by a compass-based indicator tool due to the effectsof external magnetic fields. The compass-based indicator tool interactswith a magnetic target that creates an internal magnetic field, andcauses the compass to indicate a particular position. The position ofthe compass is indicative of the setting of the implantable medicaldevice, e.g., the position of a fluid flow valve. External magneticfields, and especially the Earth's magnetic field, may interfere withthe compass and create an incorrect device setting indication.

Various embodiments of the present invention have the object of solvingthe foregoing problems. For example, it is an object of the presentinvention to overcome at least some of the disadvantages of theforegoing procedures by providing a electronic-based magnetic locationand orientation based indicator tool that produces more accurate andreliable indications of implantable device settings. To that end, it isa further object of the present invention to reduce the effects of anexternal magnetic field on the electronic-based indicator tool, andthereby enhance the accuracy of the tool. It is another object of theinvention to reduce the effects of an external magnetic field byelectronically measuring and compensating for the presence of theexternal magnetic field. The invention is also capable of sensing theimplanted magnet at a greater distance (such as in the case where thereis thick skin or scalp tissue over the implanted device) than the priorcompass-based tool. A third advantage is that the current invention isthat it is much less sensitive to alignment with the implanted device.The compass based tool must be positioned within about 1 cm or less fromcoaxial with the implanted device to provide an accurate reading. Withthe current invention, the implanted device must only be encircled bythe sensor array. Precise coaxial centering is not required.

Various embodiments of the invention may possess one or more featurescapable of fulfilling the above objects. In general, the invention isdirected to a electronic magnetic-based indicator tool that includes aplurality of magnetic field sensors and a processing system that usesdata generated from the plurality of magnetic field sensors to determinea location and orientation of a magnetic indication device. The magneticindication device, being coupled to a valve used to control operation onan implantable flow control device, permits the processing module tofurther determine a setting for the valve from the location andorientation of the magnetic indication device.

In another embodiment, the invention is directed to a system comprisingan implantable medical device that includes an implantable flow controldevice, an electronic magnetic-based indicator tool, and an adjustmenttool. The implantable flow control device includes a magnetic devicecoupled to a control valve. The electronic magnetic-based indicator toolthat includes a plurality of magnetic field sensors and a processingsystem that uses data generated from the plurality of magnetic fieldsensors to determine a location and orientation of a magnetic indicationdevice. The magnetic device, being coupled to a valve used to controloperation on an implantable flow control device, permits the processingmodule to further determine a setting for the valve from the locationand orientation of the magnetic indication device.

In another embodiment, the invention is directed to a method whichcomprises placing a electronic magnetic-based indicator tool adjacent toan implantable medical device, detecting a magnet field from a pluralityof magnetic field sensors, estimating a background magnet field from asequence of magnetic field data observed over time, and indicating adevice setting of the implantable medical device, wherein the devicesetting is indicated by the indicator tool. The plurality of targetmagnetic field sensors and the plurality of background magnetic fieldsensors are located a distance apart sufficient to permit the backgroundmagnetic field sensors to only detect ambient magnetic fields when thetarget magnetic field sensors are located near the implanted flowcontrol device.

In comparison to known implementations of magnetic-based indicator toolsfor implantable medical devices, various embodiments of the presentinvention may provide one or more advantages. For example, if theimplantable medical device is implanted subcutaneously on a patient'sskull, an electronic magnetic-based indicator tool in accordance withthe invention is capable of taking a more accurate device settingmeasurement through the patient's skin. As a magnetic-based indicatortool moves further away from the magnet contained within an implantablemedical device, external magnetic fields have a relatively greaterinfluence on the indicator tool. The magnetic sensors of the presentinvention enable estimation and compensation of the external magneticfields and thus prevent the corruption of the device settingmeasurement, even as the distance increases between the indicator tooland the implantable medical device. The electronic indicator tool isthen able to display accurate device setting values in the cases wherethe patient's skin is thicker than normal. In this way, the electronicindicator tool may eliminate the need for x-rays to determine animplantable medical device setting through a surface, such as apatient's skin.

It is a primary object of the present invention to provide animprovement to magnetic-based indicator tools for use with implantablemedical devices. This and other objects of the invention will becomeclear from an inspection of the detailed description of the inventionand from the appended claims. Throughout the description, like elementsare referred to by like reference numbers. An element referred to by areference number has all the attributes and characteristics of theelement as described wherever in the description unless specificallystated otherwise.

The above summary of the present invention is not intended to describeeach embodiment or every embodiment of the present invention or each andevery feature of the invention. Advantages and attainments, togetherwith a more complete understanding of the invention, will becomeapparent and appreciated by referring to the following detaileddescription and claims taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram illustrating a subcutaneously implantableand adjustable fluid flow control device for use with an improved valvereader device according to an example embodiment of the presentinvention.

FIG. 2 is a cross-sectional diagram further illustrating thesubcutaneously implantable and adjustable fluid flow control device ofFIG. 1.

FIG. 3 is a diagram illustrating an improved electronic valve reader andadjustment tool in accordance with an example embodiment of the presentinvention.

FIG. 4 is a block diagram illustrating a general programmable processingsystem for use in a handheld device such as an improved electronic valvereader and adjustment tool in accordance with an example embodiment ofthe present invention.

FIG. 5 is a block diagram illustrating a display showing a magneticdevice within an improved electronic valve reader and adjustment tool inaccordance with an example embodiment of the present invention.

FIG. 6 is a block diagram illustrating a set of processing moduleswithin an improved electronic valve reader and adjustment tool inaccordance with another example embodiment of the present invention.

FIGS. 7 and 8 illustrate improved implantable valve devices possessingadditional magnetic devices for used with an improved electronic valvereader and adjustment tool in accordance with an example embodiment ofthe present invention.

FIG. 9 illustrates a diagram of an improved electronic valve readerwhile used with an accompanying adjustment tool in accordance with anexample embodiment of the present invention.

FIG. 10 illustrates a flowchart of a method for use of an improvedelectronic valve reader and adjustment tool in accordance with anexample embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in the drawings for purposes of illustration, the FIGS. 1 and 2illustrate a subcutaneously implantable and percutaneously adjustablefluid flow control device, generally designated in the accompanyingdrawings by the reference numbers 10. The fluid flow control devices 10is intended for use in a surgically implanted physiological shunt systemfor draining fluid from one portion of the body to another. In order toconnect, for example, the device 10 in such a system, the deviceincludes an inlet connector 12 and an outlet connector 14 which eachreceive one end of a piece of surgical tubing (not shown). The ends ofthe surgical tubing are placed over the connectors 12 and 14 and securedthereon by a single ligature just inside of an annular ridge formed nearthe end of each connector.

When the flow control device 10 is used in a drainage system intendedfor the treatment of hydrocephalus, the inlet connector 12 is fluidlyconnected with a proximal catheter that is inserted through the skullinto a brain ventricle containing cerebrospinal fluid under pressure.The outlet connector 14 is fluidly connected to a distal catheter thatserves to discharge cerebrospinal fluid to, for example, the atriumportion of a patient's heart. Ordinarily the flow control device 10 willbe surgically implanted on the patient's skull with a flap of skinoverlying the device. To facilitate holding the device in its desiredposition after implantation, a generally flexible mounting plate can beprovided with one or more suture holes.

The highly reliable fluid flow control device has a single flow paththere through and a valve mechanism which can be percutaneously adjustedwhen the device is subcutaneously implanted by the use of the valveadjuster and reader device of the present invention. The flow controldevice 10 include a relatively rigid, molded plastic base investedwithin an elastomeric casing 16 which, together, define a fluid flowpath through the fluid flow control devices from the inlet connector 12to the outlet connector 14. The valve housing includes a percutaneouslyadjustable valve mechanism that restricts the flow of fluid through thedevice 10. Coupled to the adjustable valve mechanism is a magneticindication device that may be externally located using an indicatortool. The present invention provides an improved mechanism fordetermining the setting of the adjustable valve mechanism. The flowcontrol device is described in more detail in U.S. Pat. No. 5,637,083issued to Bertrand et al. entitled “Implantable Adjustable Fluid FlowControl Valve.”

FIG. 3 is a diagram illustrating an improved electronic valve reader andadjustment tool in accordance with an example embodiment of the presentinvention. The electronic valve reader 300 includes three maincomponents: a valve reader sensor module 303, a display module 301, andan adjustment tool 305. The valve reader sensor module 303 correspondsto the sensor mechanism that electronically determines the location andorientation of a magnetic indication device that is an integral part ofthe implanted flow control device disclosed in the '083 patent. Valvereader sensor module 303 uses a plurality of magnetic sensor devices, asdiscussed below and as disclosed in detail in the '668 and the '297patents identified above, to identify the location and orientation ofthe implanted magnetic device. Processing modules within the valvereader sensor module 303 determine a corresponding valve setting for theadjustable valve within the implanted flow control device based uponlocation and orientation of the magnetic indication device. In oneembodiment, a valve reader sensor module 303 contains the magnetic fieldsensors and some associated support electronics, while processing,display, power supply circuitry, and batteries may be contained insidethe rest of the unit 301.

From all of this information, the processing modules within the valvereader sensor modules 303 generate display data that is subsequentlyoutput to the display module 301 of the electronic valve reader 300. Thedisplay data represents a visual indication of the orientation of avalve control mechanism within the flow control device. The user of thereader may use this display data to determine whether the valve withinthe flow control device is set to a desired position.

In prior valve indicator devices, a magnetic compass has been used todetermine an orientation for the magnetic indication device that iscoupled to the valve control mechanism within the flow control device.This compass-based indication mechanism is replaced within the improvedelectronic valve reader with the electronic-based magnetic location andorientation processing system similar to the devices disclosed withinthe '668 and the '297 patents identified above. These prior patentslocate a position and orientation of a magnetic device, such as amedical tube or catheter, but fail to indicate a valve orientationsetting as a result of the determined orientation. The indicatormechanism of the present invention is less sensitive to environmentalsources of magnetic fields that required prior indicator tools to belocated extremely close to the flow control device in order to functionproperly.

When operating, the valve reader sensor module 303, and its plurality ofmagnetic sensor modules, are placed near the patient at a location inwhich the implanted flow control device is believed to be located. Inmany cases, a physician may accurately identify this location for theflow control device and the valve reader sensor module 303 may belocated on top of the implanted flow control device. The electronics inthe valve reader sensor module 303 process detected signalscorresponding to magnetic fields generated by the magnetic indicationdevice that is part of the flow control device. These electronic signalsmay also correspond to magnetic fields associated with ambient andenvironmental sources. The effects from these ambient and environmentalsources may be subtracted from the detected signals to determine a moreaccurate indication for the location and orientation of the magneticindication device that is part of the flow control device. The magneticfield data from each of the plurality of magnetic sensor modules permitsa determination of the location and orientation of a magnetic indicationdevice to be expressed in five degrees of freedom: x, y, z, pitch, andyaw.

From this determined orientation of the magnetic indication device thatis part of the flow control device and from the known orientation of theflow control device, the processing modules may determine the presentsetting for the valve within the flow control device. The processingrequired to translate the position of the magnetic indication device tothe setting of the valve within the flow control device is easilydetermined in that the value corresponds to a rotatable wheel having aposition within a circle of rotation for the magnetic indication devicethat directly corresponds to the setting of the valve within the flowcontrol device. This translation processing is well understood anddisclosed in detail within the '668 and '297 patents as the orientationof a compass within its circle of rotation directly corresponded to thesetting for the valve within the flow control device. Once the currentposition of the valve is determined and displayed, the adjustment tool305 may be used to alter the setting for the valve within the flowcontrol device.

FIG. 4 is a block diagram illustrating a general programmable processingsystem for use in a handheld device such as an improved electronic valvereader and adjustment tool in accordance with an example embodiment ofthe present invention. In an exemplary embodiment of a handheldprocessing system 400, computing system 400 is operative to provide amagnetic valve reader processing system. Those of ordinary skill in theart will appreciate that the magnetic valve reader 400 may include manymore components than those shown with reference to a computing system400 shown in FIG. 4. However, the components shown are sufficient todisclose an illustrative embodiment for practicing the presentinvention.

As shown in FIG. 4, magnetic valve reader processing system 400 is usedin connection with an implantable flow control device 10 as needed. Themagnetic valve reader processing system 400 also includes processingunit 412, video display adapter 414, and a mass memory, all connectedvia bus 422. The mass memory generally includes RAM 416, ROM 432, andmay include one or more mass storage devices, such as a removable memorydevice such as a Compact Flash, Smart Media, or Secure Digital memorycard. The memory devices may store an operating system 420 forcontrolling the operation of magnetic valve reader processing system400. It will be appreciated that this component may comprise a generalpurpose server operating system as is known to those of ordinary skillin the art, such as UNIX, MAC OS™, LINUX™, or Microsoft WINDOWS®. Basicinput/output system (“BIOS”) 418 is also provided for controlling thelow-level operation of processing system 400.

The mass memory as described above illustrates another type ofcomputer-readable media, namely computer storage media. Computer storagemedia may include volatile and nonvolatile, removable and non-removablemedia implemented in any method or technology for storage ofinformation, such as computer readable instructions, data structures,program modules or other data. The mass memory also stores program codeand data for providing a magnetic valve reader processing program. Morespecifically, the mass memory stores applications including magneticvalve reader program 430, and other programs 434, and similar analysistool applications 436 as may be needed. The magnetic valve readerprocessing program 430 includes computer executable instructions whichare executed to perform the logic described herein.

The magnetic valve reader processing system 400 also comprisesinput/output interface 424 for communicating with external devices, suchas a touch screen and similar input devices, or other input devices notshown in FIG. 4. Likewise, The magnetic valve reader processing system400 may further comprise additional mass storage facilities also notshown should additional data storage be needed.

One skilled in the art will recognize that the processing systemillustrated within FIG. 4 may represent a set of processing componentstypically found within a handheld or similar dedicated processingsystem. Of course, other processing systems including general purposecomputing systems containing additional peripherals and user interfacedevices may also be used to implement the programmable processingaccording to various embodiments of the present invention withoutdeviating from the spirit and scope of the present invention as recitedwithin the attached claims.

FIG. 4 illustrates an example of a suitable operating environment inwhich the invention may be implemented. The operating environment isonly one example of a suitable operating environment and is not intendedto suggest any limitation as to the scope of use or functionality of theinvention. Other well known computing systems, environments, and/orconfigurations that may be suitable for use with the invention include,but are not limited to, personal computers, server computers, hand-heldor laptop devices, multiprocessor systems, microprocessor-based systems,programmable consumer electronics, network PCs, minicomputers, mainframecomputers, distributed computing environments that include any of theabove systems or devices, and the like. For example, a dedicatedprocessing system may consist of a digital signal processer (DSP) forperforming the required floating-point math, various internal memorytypes including FLASH, ROM, RAM, and FPGA, some minimal external memoryfor the valve calibration system, and a user interface and displaydriver chip to run the switches and custom LCD display. A proprietaryembedded operating system is and a specifically written application forimplementing the reader program may be included.

The invention may also be described in the general context ofcomputer-executable instructions, such as program modules, executed byone or more computers or other devices. Generally, program modulesinclude routines, programs, objects, components, data structures, etc.that perform particular tasks or implement particular abstract datatypes. Typically the functionality of the program modules may becombined or distributed as desired in various embodiments.

Processing devices typically include at least some form of computerreadable media. Computer readable media can be any available media thatcan be accessed by these devices. By way of example, and not limitation,computer readable media may comprise computer storage media andcommunication media. Computer storage media includes volatile andnonvolatile, removable and non-removable media implemented in any methodor technology for storage of information such as computer readableinstructions, data structures, program modules or other data. Computerstorage media includes, but is not limited to, RAM, ROM, EEPROM, flashmemory or other memory technology, CD-ROM, digital versatile disks (DVD)or other optical storage, magnetic cassettes, magnetic tape, magneticdisk storage or other magnetic storage devices, or any other mediumwhich can be used to store the desired information and which can beaccessed by processing devices.

Communication media typically embodies computer readable instructions,data structures, program modules or other data in a modulated datasignal such as a carrier wave or other transport mechanism and includesany information delivery media. The term “modulated data signal” means asignal that has one or more of its characteristics set or changed insuch a manner as to encode information in the signal. By way of example,and not limitation, communication media includes wired media such as awired network or direct-wired connection, and wireless media such asacoustic, RF, infrared and other wireless media. Combinations of any ofthe above should also be included within the scope of computer readablemedia.

Additionally, the embodiments described herein are implemented aslogical operations performed by a programmable processing devices. Thelogical operations of these various embodiments of the present inventionare implemented (1) as a sequence of computer implemented steps orprogram modules running on a computing system and/or (2) asinterconnected machine modules or hardware logic within the computingsystem. The implementation is a matter of choice dependent on theperformance requirements of the computing system implementing theinvention. Accordingly, the logical operations making up the embodimentsof the invention described herein can be variously referred to asoperations, steps, or modules.

FIG. 5 is a block diagram illustrating a magnetic device within animproved electronic valve reader and adjustment tool in accordance withan example embodiment of the present invention. The electronic valvereader 500 includes an opening 501 within the reader 500 that permitsthe reader 500 to be positioned over an implanted flow control device.The reader also includes a plurality of magnetic sensor devices 510-513that each detect the magnetic field at their respective locations withinreader 500. The magnetic field detected by each sensor 510-513 at itslocation is due to both background environmental magnetic fields andthat arising from a magnetic device 520 located within the opening 501.As such, signals from the various magnetic sensor devices 510-513 may beprocessed to determine a location and orientation of the magnetic device520 relative to the known positions of the magnetic sensor devices510-513.

When the magnetic device 520 that is detected by the plurality ofmagnetic sensors corresponds to a magnetic indication device that ispart of the valve within a flow control device, it is desired todetermine the orientation of the magnetic indication device relative toa known position of the flow control device in order to accuratelydetermine the setting for the valve within the flow control device. Inone embodiment, the user orients the electronic valve reader to a knownorientation relative to the implanted flow control device. As such, theorientation of the magnetic indication device, and thus the valve, isdetermined relative to this known orientation. Prior indicator toolsthat utilize a compass-based indicator required users to orient thetools relative to the flow control device to perform this identicaldetermination. In other embodiments, additional measurements foradditional position references may be used to perform this orientationand position translation operation. Because processing within the reader500 may be updated periodically, and may occur several times per second,ambient and environmental sources of magnetic fields may be estimatedand subtracted from the observed signals generated by the plurality ofmagnetic sensor devices 510-513. These magnetic sensor devices 510-513are generally located at dispersed locations about the reader. In oneembodiment, these sensors 510-513 may be located about one of therespective four corners of the reader. Use of these sensors in thisfashion permits the reader device to sense implanted magnetic devices atgreater distances while being less sensitive to being centered coaxiallyover the implanted flow control device as compared to compass-baseddevices.

FIG. 6 is a block diagram illustrating a set of processing moduleswithin an improved electronic valve reader and adjustment tool inaccordance with another example embodiment of the present invention. Theelectronic valve reader 600 is constructed using a display module 610that is surrounded by a plurality of magnetic field sensor modules601-604. Each of these four sets of magnetic field sensors 601-604contain three separate sensors so as to measure the full,three-dimensional vector magnetic field detected by the module at itslocation. The reader 600 also contains an analog-to digital convertermodule 621 and an combined magnetic field sensor module 611 toelectronically process the signals generated by the magnetic fieldsensor modules 601-604 to obtain digital measurements corresponding theobserved magnetic field.

These digital measurements of the observed magnetic field aresubsequently processed within a processing module 620 to determine thelocation and orientation of a magnetic device within a field of view forthe reader 600. The processing module corresponds to a programmableprocessing system as discussed above with respect to FIG. 4. Theprocessing module performs operations upon the measured magnetic fielddata to determine the magnetic field generated by the magnetic devicewhile subtracting an estimate for ambient and environmental magneticfield also observed by the magnetic field sensors 601-604. Theprocessing performed in this determination of the location andorientation of the magnetic indication device is described in moredetail within the '668 and the '397 patents to Haynor et al. discussedabove.

From the above location and orientation of the magnetic device relativeto the implantable flow control device, the processing module furtherdetermines the setting of the valve. This setting data is then used togenerate a display image to be presented to a user on the display module610. The processing module 620 outputs the display data to the displaymodule 610 through a display driver 612.

The device may further contain a memory card reader 631 for acceptingcomputer readable storage media. In one embodiment, this storage mediamay include compact flash, start media, secure digital, and memory stickmemory cards for providing the device replaceable memory containing datausable by the device. For example, an implantable flow control devicemay permit fluid to flow at a particular pressure setting thatcorresponds to a particular setting on the valve. When the readerdetermines the valve setting, the data from the memory card may be usedto display the corresponding pressure setting. Because thevalve-to-pressure setting may vary from particular models of implantableflow control devices, the use or a memory card corresponding to themodel of the flow control device will permit the reader device to easilydisplay pressure values for a wide variety of flow control deviceswithout needing to maintain all of the valve to pressure setting datafor all devices at one time.

FIGS. 7 and 8 illustrate improved implantable valve devices possessingadditional magnetic devices for used with an improved electronic valvereader and adjustment tool in accordance with an example embodiment ofthe present invention. As discussed above, the location and orientationof a detected magnetic device that is coupled to an implantable flowcontrol device is used relative to an estimated position of the flowcontrol device to determine the valve setting. This estimate is madebecause the valve is set by positioning the magnetic device coupled tothe valve such that as the valve rotates about a known circularposition, the magnetic field of the magnetic device also rotates aboutthe same circle. In existing indicator tools, the tools must be alignedmanually by a user into an orientation aligned with the implanted flowcontrol device. This alignment process is also used in one embodiment ofthe electronic valve reader as discussed above.

In an alternate embodiment, an additional magnet 710 is coupled to theimplantable flow control device 700 in a location separate from thevalve 701 and its magnetic indicator device 703. The electronic reader,using the same processing to detect the magnetic device as discussedabove, detects the location and orientation of the additional magnet710. The location of the additional magnet 710 provides a referencepoint for the processing modules within the electronic valve reader toexpressly determine the orientation of the electronic valve reader. Thereader does not require the implanted flow control device to be positioninto a known orientation relative to the reader in order to accuratelydetermine the setting of the valve. In this alternate embodiment, thesetting of the valve may be made by determining the orientation of themagnetic device 703 coupled to the valve 701 relative to the position ofthe additional reference magnet 710. Using this method, the setting ofthe valve may be made accurately, yet independently of the orientationof the reader to the implanted flow control device.

In yet another embodiment, two separate reference magnets 810-811 areadded to flow control device 800 so that the orientation of the valve801 and its corresponding magnetic indicator device 803 independently ofthe position of the reader. This second embodiment also works withseparate embodiment of the reader. In alternate embodiment for thereader, the reader may utilize less magnetic sensors. The sensors wouldprovide information regarding the general orientation of the detectedmagnetic fields. When the user orients the reader in this embodimentinto a desired orientation aligned with the implanted flow controldevice, the setting of the valve 801 may be determined from theorientation of the magnetic fields observed from the magnetic indicatordevice 803 coupled to the valve 801.

FIG. 9 illustrates a diagram of an improved electronic valve readerwhile used with an accompanying adjustment tool in accordance with anexample embodiment of the present invention. In this embodiment, thereader 901 contains a display module 911 that displays the position ofthe valve once the reader 901 is positioned near an implanted flowcontrol device. This process of determining the position of the valve isdiscussed above in detail.

Once the current position of the valve is determined and displayed, theadjustment tool 905 may be used to alter the setting for the valvewithin the flow control device. The adjustment tool corresponds to amagnetic coupling device that is placed over the valve reader sensormodule 903 to orient the adjustment tool directly over the magneticindication device that is part of the valve. The adjustment tool 905magnetically couples to the magnetic indication device such that arotation of the adjustment tool 905 within its location at above thevalve reader sensor module 903 causes the magnetic indication device torotate within the valve. This rotation of the magnetic indication devicechanges the settings for the valve within the flow control device as themagnetic indication device is directly coupled to the valve settingmechanism. The operation of the adjustment tool 905 is disclosed inadditional detail with the published U.S. Patent application to Bertrandet al., No. 2002/0022873 as identified above. These modules operatetogether as disclosed herein to provide the operation of an electronicvalve reader and valve adjustment tool.

FIG. 10 illustrates a flowchart of a method for use of an improvedelectronic valve reader and adjustment tool in accordance with anexample embodiment of the present invention. The method for determiningthe setting of a valve within an implantable flow control device beginsby determining an estimate for background magnetic fields 1001. Thisvalue is determined by obtaining a set of magnetic field values that areaveraged to obtain this estimate for the background fields fromenvironmental and ambient sources. Next, the method continues by placing1003 of the reader near the implantable flow control device within apatient. Because the magnetic field typically observable at a distanceof 12 cm from a typical magnetic indicator device coupled to animplantable flow control device is generally less than 5 milliGauss, thereader must be placed as close as possible to the flow control device topermit the reader to detect this magnetic field within the Earth'sbackground magnetic field typically observed to be approximately 500milliGauss.

Once the reader is located as close to the flow control device aspossible, the reader detects an observed magnetic field 1005 from allsources. The background magnetic fields estimate 1001 is subtracted fromthe observed values 1005 to obtain a position and orientation for themagnetic indicator device 1007 coupled to the valve that is part of theimplanted flow control device. The detected magnetic field measurementsand processed position and orientation for the magnetic indicator deviceare repeated at a rate of several times per second.

The orientation of the magnetic indicator device is compared to a knownorientation of the flow control device to determine a setting 1009 forthe valve of the flow control device. The known orientation of the flowcontrol device may be manually determined by requiring the reader to beoriented to a particular position relative to flow control device. Theknown orientation of the flow control device may also be determined froma detection of other reference positions, such as a separate referencemagnet as discussed above. Once the reader has determined the settingfor the valve, a user may utilize an adjustment tool to magneticallyrotate and thus alter the setting of the valve as desired.

In the claims, any means-plus-function clauses are intended to cover thestructures described herein as performing the recited function and notonly structural equivalents but also equivalent structures. Thus,although a nail and a screw may not be structural equivalents in that anail employs a cylindrical surface to secure wooden parts together,whereas a screw employs a helical surface, in the environment offastening wooden parts a nail and a screw are equivalent structures.

Many embodiments of the invention have been described. Variousmodifications may be made without departing from the scope of theclaims. These and other embodiments are within the scope of thefollowing claims.

1. An electronic magnetic-based indicator tool comprising: a housinghaving an electronic display; a plurality of magnetic field sensors, theplurality of magnetic field sensors grouped into sets of magnetic fieldsensors to determine spatial location and orientation of a magneticindicator device associated with a valve of an implantable flow controldevice; and a processing module that receives magnetic data values fromthe plurality of magnetic field sensors and determines a setting for thevalve on the implantable flow control device using the determinedorientation of the magnetic indicator device.
 2. The electronicmagnetic-based indicator tool according to claim 1, wherein theprocessing module further determines the setting of the valve on theimplantable flow control device using a determined orientation of areference magnet coupled to the implantable flow control device at alocation separate from the magnetic indicator device.
 3. The electronicmagnetic-based indicator tool according to claim 1, wherein theprocessing module generates a display image corresponding to anorientation of the valve relative to the implantable flow control deviceand outputs the display image on the electronic display.
 4. Theelectronic magnetic-based indicator tool according to claim 1, whereinthe processing module determines an estimate for ambient magnetic fieldsfrom a sequence of magnetic data values from the plurality of magneticfield sensors.
 5. The electronic magnetic-based indicator tool accordingto claim 4, wherein the processing module further subtracts the estimatefor ambient magnetic fields from received magnetic data values todetermine the setting of the valve on the implantable flow controldevice.
 6. The electronic magnetic-based indicator tool of claim 1,wherein the plurality of magnetic field sensors comprises four sets ofthree sensors for determining location and orientation of the magneticindicator device in five degrees of freedom.
 7. The electronicmagnetic-based indicator tool of claim 6, wherein each of the four setsof three sensors being located about a respective one of four corners ofthe indicator tool.
 8. The electronic magnetic-based indicator toolaccording to claim 1, wherein the indicator tool further comprises anadjustment tool that modifies an orientation of the valve in theimplantable flow control device.
 9. The electronic magnetic-basedindicator tool according to claim 8, wherein the adjustment toolcomprises a magnetic adjustment component that magnetically couples tothe magnetic indicator device of the flow control device.
 10. Theelectronic magnetic-based indicator tool according to claim 9, whereinrotating the adjustment tool while the magnetic adjustment component ismagnetically coupled to the magnetic indicator device of the flowcontrol device causes the valve of the flow control device to rotatechanging the setting of the valve.
 11. The electronic magnetic-basedindicator tool according to claim 1, wherein the tool further comprises:a removable data storage device, the data storage device containingcomputer readable data that translates the setting of the valve to apressure for the implantable flow control device.
 12. The electronicmagnetic-based indicator tool according to claim 11, wherein theremovable storage device being from a group of removable data storagedevices consisting of compact flash memory device, a secure digitalmemory device, a smart media storage device, and a memory stick memorydevice.
 13. The electronic magnetic-based indicator tool according toclaim 11, wherein computer readable data that translates the setting ofthe valve to the pressure for the implantable flow control devicecorresponds to a particular model of the implantable flow controldevice.
 14. The electronic magnetic-based indicator tool according toclaim 11, wherein the indicator tool further comprises user controlsthat activate operation of the tool and a power supply.
 15. Theelectronic magnetic-based indicator tool according to claim 14, whereinthe power supply comprises a removable battery.
 16. A system comprising:an implantable medical device comprising a magnetic indicator deviceassociated with a valve of an implantable flow control device thatindicates a current setting of the implantable flow control device; anelectronic magnetic-based indicator tool comprising: a housing having anelectronic display; a plurality of magnetic field sensors, the pluralityof magnetic field sensors grouped into sets of three magnetic fieldsensors; and a processing module that receives magnetic data values fromthe plurality of magnetic field sensors and determines a setting for thevalve on the implantable flow control device using a determinedorientation of the magnetic indicator device coupled to the valve; andan adjustment tool that modifies an orientation of the valve in theimplantable flow control device, the adjustment tool comprises amagnetic adjustment component for magnetically coupling to the magneticindicator device of the flow control device.
 17. The system according toclaim 16, wherein the processing module further determines the settingof the valve on the implantable flow control device using a determinedorientation of a reference magnet coupled to the implantable flowcontrol device at a location separate from the magnetic indicatordevice.
 18. The system according to claim 16, wherein the processingmodule generates a display image corresponding to the setting of theimplantable flow control device and outputs the display image on theelectronic display.
 19. The system according to claim 16, wherein theprocessing module determines an estimate for ambient magnetic fieldsfrom a sequence of magnetic data values from the plurality of magneticfield sensors.
 20. The system according to claim 19, wherein theprocessing module further subtracts the estimate for ambient magneticfields from received magnetic data values to determine the setting ofthe valve on the implantable flow control device.
 21. The systemaccording to claim 16, wherein the tool further comprises: a removabledata storage device, the data storage device containing computerreadable data that translates the setting of the valve to pressure forthe implantable flow control device.
 22. The system according to claim21, wherein the removable storage device being from a group of removabledata storage devices consisting of compact flash memory device, a securedigital memory device, a smart media storage device, and a memory stickmemory device.
 23. The system according to claim 21, wherein computerreadable data that translates the setting of the valve to pressure forthe implantable flow control device corresponds to a particular model ofthe implantable flow control device.
 24. The system according to claim21, wherein the indicator tool further comprises user controls thatactivate operation of the tool and a power supply.
 25. The systemaccording to claim 24, wherein the power supply comprises a removablebattery.
 26. A method comprising: placing an electronic magnetic-basedindicator tool adjacent to an implantable medical device, theimplantable medical device having a magnetic indicator device coupled toa valve used to control operation of the medical device; measuring amagnetic field strength observed by the indicator tool; estimating aportion of the observed magnetic fields caused by an environmentalmagnetic field; determining an orientation of the magnetic indicatordevice relative to a known position of the implantable medical deviceusing the observed magnetic field and the estimate for the environmentalmagnetic field; and indicating a device setting of the implantablemedical device.
 27. The method according to claim 26, wherein the knownposition of the implantable medical device is determined from anexpected orientation of the indicator tool relative to the implantablemedical device.
 28. The method according to claim 26, wherein the knownposition of the implantable medical device is determined fromdetermining a location and orientation of a reference magnetic devicecoupled to the implantable medical device.
 29. The method according toclaim 26, wherein the measuring the magnetic field comprises: receivingelectronic signals from a plurality of magnetic field sensors, themagnetic field sensors grouped into a plurality of sets of three sensorslocated at separate locations within the indicator tool; and processingthe received electronic signals to determine an orientation and locationof a magnetic device.
 30. The method according to claim 29, wherein theplurality of sets of three sensors comprise four sets of sensors, eachof the four sets of sensors being located about a respective one of fourcorners of the indicator tool.